Presbyterianism is a branch of Protestant Christianity that adheres to the Calvinist theological tradition and whose congregations are organized according to a Presbyterian polity. Presbyterian theology typically emphasizes the sovereignty of God, the authority of the Scriptures, and the necessity of grace through faith in Christ. Presbyterianism originated primarily in Scotland. Scotland ensured Presbyterian "church government" in the Acts of Union in 1707 which created the kingdom of Great Britain. In fact, most Presbyterians found in England can trace a Scottish connection, and the Presbyterian denomination was also taken to North America mostly by Scots and Scots-Irish immigrants^{[citation needed]}. The Presbyterian denominations in Scotland hold to the theology of Calvin and his immediate successors, although there is a range of theological views within contemporary Presbyterianism.

Modern Presbyterianism traces its institutional roots back to the Scottish Reformation. Local congregations are governed by Sessions made up of representatives of the congregation, a conciliar approach which is found at other levels of decision-making (Presbytery, Synod and General Assembly). Theoretically, there are no bishops in Presbyterianism; however, some groups in Eastern Europe, and in ecumenical groups, do have bishops. The office of elder is another distinctive mark of Presbyterianism: these are specially ordained non-clergy who take part in local pastoral care and decision making at all levels. The office of deacon is geared toward the care of members, their families, and the surrounding community. In some congregations active elders and deacons serve a three-year term and then rotate off for at least a year. The offices of pastor, elder, and deacon all commence with ordination; once a person is ordained, he holds that title for the rest of his life. An individual may serve as both an elder and a deacon.

John Knox (c. 1514 – 24 November 1572) was a Scottish clergyman and a leader of the Protestant Reformation who brought reformation to the church in Scotland. He was educated at the University of St Andrews or possibly the University of Glasgow and was ordained to the Catholic priesthood in 1536. Influenced by early church reformers such as George Wishart, he joined the movement to reform the Scottish church. He was caught up in the ecclesiastical and political events that involved the murder of Cardinal Beaton in 1546 and the intervention of the regent of Scotland, Mary of Guise. He was taken prisoner by French forces the following year and exiled to England on his release in 1549.

While in exile, The Rev. John Knox was licensed to work in the Church of England, where he quickly rose in the ranks to serve King Edward VI of England as a royal chaplain. In this position, he exerted a reforming influence on the text of the Book of Common Prayer. In England he met and married his first wife, Marjorie. When Mary Tudor ascended the throne and re-established Roman Catholicism, Knox was forced to resign his position and leave the country.